1. Field of the Invention
An embodiment relates to a secondary battery and, more particularly, to a secondary battery capable of reducing poor welding or soldering between metal tabs while improving the binding force between a metal tab of a protecting circuit module (PCM) and a metal tab of a secondary protection device.
2. Discussion of Related Art
In general, a secondary battery is a battery in which inter-conversion between chemical energy and electrical energy is reversible, such that charging and discharging can repetitively be performed. Secondary batteries are raising a lot of interest as a driving power supply for mobile and portable IT devices due to their decrease in weight and increase in functionality.
The secondary battery includes a nickel-cadmium battery, a nickel-hydrogen battery, a nickel-zinc battery, a lithium secondary battery, etc. Among them, since the lithium secondary battery is rechargeable and can have a small size, a high capacity, a high operating voltage and high energy density per unit weight, lithium batteries are widely used in an advanced electronic apparatus field Lithium batteries include lithium-ion batteries, lithium-ion polymer batteries, lithium polymer batteries, etc.
The secondary battery in the related art includes safety devices, such as the protecting circuit module (PCM) and the secondary protection device, in order to prevent an increase in high temperature, overcharge and overdischarge, or the like. In addition, the PCM and the secondary protection device may be provided together. In this case, a secondary protection device is connected to one end of the PCM and a cell is connected to the other end of the PCM. Further, the secondary protection device is attached between the cell and the PCM and likewise protects the cell from overcurrent and heat emission of the cell.
In addition, the secondary protection device is connected to the PCM through welding to the metal tab seated on the PCM and, in this process, a problem often occurs. Since the position where the metal tab outside of the PCM is typically seated may be spaced from a position where the metal tab of the secondary protection device is typically seated, poor welding can occur or one-side of a metal tab is spaced apart during welding of the metal tabs.